<p>The geo-neutrino flux at the Sudbury Neutrino Observatory depends on the local level of crustal radioactivity, which is best estimated from surface heat flux data. The surface heat flux records average crustal radio-activity over the whole crustal column and is unaffected by small-scale heterogeneities. We show how the contribution of crustal heat sources to the geo-neutrino flux can be calculated from knowledge of the surface heat flux. We present new heat flux data from two very deep holes (>2000 m) in the Sudbury structure as well as measurements of U, Th, and K concentrations in the main geological units of the area. With all available data, the average heat flux in the Sudbury basin is approximate to 53 mW m(-2), higher than the mean value of 42 mW m(-2) for the entire Canadian Shield. The elevated heat flux is due to high heat production in the shallow crust and implies an at least 50% increase of the local crustal component of the geo-neutrino flux relative to that expected for the average crustal composition of the shield. (C) 2009 Elsevier B.V. All rights reserved.</p>
Perry, H. K. C. Mareschal, J-C. Jaupart, C.